The present invention relates to boxes for produce and the like and, more particularly, to such boxes that are capable of being stacked to considerable height without collapsing or becoming unstable.
When agricultural produce such as grapes and strawberries are picked, it is packed in the field in relatively flat, open-topped trays or boxes. These boxes are stacked on pallets for shipping and storage, a stack often being sixteen, eighteen or more boxes high.
Since the boxes are generally used only once and are consumed in large numbers, running into many millions each growing season, their cost must be kept to a minimum, yet they must be strong enough to protect the produce against degradation. They should be lightweight and have a maximum capacity in comparison to their external dimensions. Generally, they are made from folded paperboard blanks and commonly include wire inserts in their end walls by which they are interlocked when stacked vertically.
Great attention has been given to the details of construction to provide the strongest boxes at the lowest cost. Many small variations have been proposed in the manner in which blanks are cut and scored in an effort to advance the art. Nevertheless, a persistent problem and limiting factor in the construction of these boxes is the strength of the end walls. When the boxes are stacked, the end walls of the lower boxes must bear the weight of the boxes above. If the end walls are partially crushed, the stack may begin to lean and become unstable. It is the required strength of the end walls that usually determines the weight of the paperboard to be used.
The need for end walls that can withstand high vertical compressive forces has also dictated that the corrugated blanks must be arranged so that the flutes of the end walls extend vertically. Unfortunately, this construction necessitates that the flutes in the bottom of the box run the long way between the end walls, thereby providing a floor that has considerably less strength and resistance to sag than a box with the floor flutes running parallel to the end walls.
A primary objective of the present invention is to provide a box of improved strength and rigidity that can be stacked higher with greater stability. A further objective is to provide such a box in which the end walls need not support the combined weight of all the boxes above.